Green groups are suing the European Commission over what they see as a failure to meet its legal commitment to transparency regarding information in decisions relating to the sustainability of Europe's biofuels policy.

A lawsuit filed on Wednesday by law organisation ClientEarth, Friends of the Earth Europe, FERN and Corporate Europe Observatory alleges that the Commission has refused the groups access to information about voluntary certification schemes used to ensure compliance with EU criteria on biofuel sustainability set out in the Renewable Energy Directive (RED).

The groups are concerned that the EU may meet its target of sourcing 10 per cent of transport energy from renewable sources using biofuels that, without proper oversight, could be competing with food crops or grown in biodiverse areas cleared for agriculture.

The Commission is looking to accredit at least one certification scheme to ensure that the RED criteria are met, and a committee will meet on Friday to discuss a series of seven programmes.

However, the groups behind the lawsuit say that the process has lacked transparency, and that neither assessment criteria nor information on other schemes being considered have been made publicly available.

They say the Commission rejected a request made last year to obtain information on the organisations that had applied to operate the schemes and how they were chosen.

This decision was challenged in December, but the groups claim that the Commission has yet to respond despite having a deadline of 4 February to do so. The Commission had not commented at time of press.

James Thornton, ClientEarth's chief executive, said that the policies were too important to decide in secrecy. "The amount of money at stake over Europe's biofuels policy is colossal, and so is the potential for environmental devastation," he said.

"We need to know which organisations have applied to run voluntary certification schemes, and how they've been chosen, so that we can be certain that they will provide robust and reliable information."

Robbie Blake, Friends of the Earth Europe's campaigner on agrofuels, accused the EU of acting contrary to its own requirements. "The European Commission has continually evaded its legal responsibility to disclose even the most basic information about voluntary certification schemes for Europe's biofuels," he said.

"The stakes are high - ineffective certification schemes will give the green light to environmental abuse. We need transparency and participation in EU policy making - not secrecy and suspicion."